Circular saw

ABSTRACT

The circular saw includes a movable blade guard mounted for rotation about an axis offset from the axis of rotation of the circular blade, such guard enclosing a kerf guide and the teeth on the lower portion of the blade. The movable blade guard is retracted by a manually operable lever mounted on the side of the fixed blade guard adjacent the motor housing. The kerf guide is adjustably mounted so as to be rocked in its own plane thereby to cooperate with circular blades of different diameters.

United States Patent Gronke et a1.

[ 1 Oct. 31, 1972 [541 CIRCULAR SAW [72] Inventors: Ronald E. Gronke, Des Plaines; Wil- 11am H. Schultz, Northbrook, both of I11.

[7 3] Assignee: Skil Corporation, Chicago, Ill.

[22] Filed: July 27, 1970 [2]] Appl. No.: 58,530

[56] References Cited UNITED STATES PATENTS 2,801 ,654 8/1957 Utz ..143/159 H I, n g g\\\ r l I 3 i 816,326 3/1906 Hill 143/159 T 3,221,783 12/1965 Kaltenmark et al 143/43 R 2,346,961 4/1944 Gundelfinger et al. 143/43 F Primary ExaminerAndrew R. J uhasz Assistant Examiner-James F. Coan Attorney-McDougall, Hersh 8:. Scott [57] ABSTRACT The circular saw includes a movable blade guard mounted for rotation about an axis offset from the axis of rotation of the circular blade, such guard enclosing a kerf guide and the teeth on the lower portion of the blade. The movable blade guard is retracted by a manually operable lever mounted on the side of the fixed blade guard adjacent the motor housing. The kerf guide is adjustably mounted so as to be rocked in its own plane thereby to cooperate with circular blades of difi'erent diameters.

12 Claims, 4 Drawing Figures PATENTEDncrst me 3701.369

Slim 1 I 3 INVENTORS RONALD E. GRGVKE WILLIAM H SCHULTZ mimannm SHEET 2 0f 3 INVENTORS RONALD E GRONKE WILLIAM H. SCHULTZ PATENTEUHBI 31 m2 ME! 3 OF 3 INVENTURS RONALD E. GRONKE ATr'Ys CIRCULAR SAW OBJECTS OF THE INVENTION A primary object of the present invention is the provision of a new and improved circular saw having a number of features contributing to safe operation of such saw.

Another object of the present invention is the provision of a new and improved circular saw having a movable blade guard adapted to enclose both a kerf guide and the teeth on the lower portion of a circular blade.

Another object of the present invention is the provision of a new and improved circular saw having a movable blade guard and a retracting mechanism therefor, such mechanism being operated by a lever mounted from the side of the fixed blade guard adjacent the motor housing.

Still another object of the present invention is the provision of a new and improved circular saw having a fixed blade guard and a movable blade guard, which movable blade guard, in the closed position thereof, cooperates with the fixed blade guard to enclose substantially the entire periphery of a circular blade.

Another object of the present invention is the provision of a new and improved circular saw having an adjustably mounted kerf guide, the means mounting said kerf guide causing rocking movement of the latter in its own plane so as to cooperate with circular blades of different diameters.

These and other objects and advantages of the invention will become apparent from the following specification disclosing a preferred embodiment shown in the accompanying drawings.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a circular saw embodying the present invention;

FIG. 2 is an enlarged section taken generally along the line 22 of FIG. 1 and showing a circular blade mounted on the motor driven shaft;

FIG. 3 is an enlarged section taken generally along the line 3-3 of FIG. 2, with the circular blade being removed and with a portion of the fixed blade guard being shown in side elevation for illustrating the means adjustably mounting the kerf guide; and

FIG. 4 is an enlarged isometric view of a portion of the tool with a part of the fixed blade guard being broken away and with the circular blade being removed.

DESCRIPTION OF A PREFERRED EMBODIMENT Referring to FIG. I, a circular saw embodying the present invention includes a motor housing mounting a handle 11, which handle may support an auxiliary handle in the form of a knob 12. The saw includes the usual base plate 13, which base plate is mounted for vertical adjustment by a knob 14 and for angular adjustment by another knob 14a.

The housing 10 mounts an electric motor 15 by means of bearing assemblies 16 and I7 engaged with respective opposite ends of the armature shaft 18. Such shaft is splined, as at 180, and is in driving engagement with a gear 20 mounted on a shaft 21, the latter being journaled in a roller bearing assembly 22 and in a ball bearing assembly 23. The drive shaft 21 includes a threaded blind bore (not shown) for receiving a screw 24, the latter supporting a washer 25 and serving to mount a circular blade 26 on the drive shaft 21.

The housing 10 mounts a fixed blade guard having an inner wall portion 28, an outer wall portion 29 and a connecting wall portion 30. The fixed blade guard is of general semicircular configuration and encloses the teeth on the upper one-half portion of the circular saw.

As noted in FIG. 2, the housing 10 includes a formation 32 encircling the shaft 21; this formation defines an annular bearing surface 324 having a central axis 33 (FIG. 3)parallel with and in spaced relation to the central axis 34 of the shaft 21. This bearing surface rotatably mounts a ring formation 35, the latter being integral with an inner wall portion 36 of a movable blade guard. This movable guard also includes a connecting wall portion 38. The movable blade guard is retained on the bearing surface 324 by a split ring 39 received in an annular groove in such bearing surface. It will be understood that by reason of the aforedescribed construction, the movable blade guard is mounted for rotation about the axis 33 which is offset from or eccentric to the axis 34 which defines the axis of rotation of the circular blade 26.

A flexible member 40 is wrapped around a portion of the ring 35 and has one end thereof connected to a flange 350 as by means of a stud 41; the flange is mounted on the ring 35 for movement therewith. The other end of the member 40 is pivotally connected to an arm 42, the latter being mounted on a pin 43. This pin is journaled in an aperture 28a formed in the fixed guide wall portion 28. An operating handle or lever 44 is mounted on the pin 43 so as to impart rotation to the latter. It will be understood that rotation of the handle 44 serves to rotate or retract the movable blade guard.

The movable blade guard is urged toward the closed position thereof as shown in the drawings by means of a coil spring 47, one end of the latter being connected to the ring flange 35a and the other end thereof being secured to the wall portion 28 ofthe fixed blade guard. A stop (not shown) is engaged by the edge 36b of the movable blade guard to limit counterclockwise rotation of the latter. As is known to those skilled in the art, this stop is preferably mounted for movement with the base plate 13 so that as the latter is adjusted vertically, the movable blade will be automatically rotated to maintain the proper relationship between the same and the base plate.

The wall portion 29 of the fixed blade guard mounts a block 50, the latter having a pair of threaded openings (not shown) threadingly receiving a pair of fasteners 51, 52. A bracket has a wall portion 53 con taining a pair of slots 54, 55, which slots receive the shanks of respective fasteners 51, 52. This bracket has another wall portion 57 in parallel relation with the wall portion 53 and integral therewith by means of a connecting wall portion 58. The wall portion 51 mounts a kerf guide 60, the latter having a distal end portion 600 and an arcuate leading edge 6% adjacent the distal end. It will be understood that the kerf guide 60 is coplanar with the blade 26 and adapted to enter the kerf formed by the latter.

As noted in FIG. 3, the slots 54, 55, although generally perpendicular to radii of the blade, are not in parallel relation with each other, but rather diverge in a generally upward direction such that the upper ends of the slots are spaced a greater distance from each other than the lower ends of such slots. in FIG. 3, the lterf guide is shown mounted in the desired position when the saw has a blade 26, the periphery of which is shown in phantom lines in this figure. According to one set of standards, the edge 60b is spaced five-sixtyfourths inch from the blade and the distal end 600 is one-eighth inch above the lowermost portion of the blade. As this blade is sharpened, its diameter is reduced; the outer periphery of such sharpened blade is shown in phantom lines and designated 26. The kerf guide 60 may be adjusted so as to cooperate with the blade represented by the phantom line 26'. To this end, the fasteners 51, 52 are loosened and the bracket is slid upwardly to the phantom line position shown in FIG. 3. Due to the nonparallel relationship of the slots 54, 55, the bracket is rocked shown in phantom lines, this movement imparting corresponding rocking movement to the kerf guide 60 such that the same occupies the position shown as 60'. This rocking action of the kerf guide in its own plane permits the same to be adjusted to establish optimum spacing between the smaller diameter blade 26' and the leading edge 60!) of the kerf guide adjacent its distal end 600. Or in other words, this camming feature of the slots 54, 55 permits a predetermined spacing to be maintained between the distal end of the kerf guide and circular blades of different diameters. For example, by this camming arrangement, the lterf guide may be adjusted with respect to the blade 26' to maintain the 5/64 and A dimensions mentioned above.

As observed in FIG. 3 (which shows the base plate 13 in the uppermost position thereof), when the movable blade guard is in its closed position, substantially the entire periphery of the circular blade is enclosed. in this closed position of the movable blade guard, the only portion of the blade which is exposed is an approximate sector as defined by the leading end 62 of the movable blade guard and the adjacent forward end portion 63 of the fixed blade guard. This sector is of course increased as the base plate 13 is adjusted to a lower position. However, the close relationship between the underside of the base plate and the leading end 62 of the movable blade guard as shown in FIG. 3 is maintained irrespective of the position of the base plate. Because of this closely spaced relationship between the forward end of the fixed blade guard and the base plate, a roller 64 is mounted on the latter, such roller being arranged to engage the work to facilitate opening of the lower blade guard. of course, the movable blade guard may be retracted before engagement with the work by manual operation of the handle 44.

It should be apparent that the present invention provides a new and improved circular saw having significant safety features. In this regard, the operator may retract the movable blade guard without bringing his hand into proximity with the movable blade guard or any exposed portion of the blade. Also, safe operation results from the fact that a maximum portion of the periphery of the circular blade is enclosed when the movable guard is in its closed position thereby minimizing the chances of the operators fingers coming into contact with the teeth on the saw blade. The eccentrically mounted movable blade guard encloses the kerf guide as well as a substantial number of the teeth on the lower portion of the circular blade. This feature obviates slotting of the movable blade guard to accommodate the lterf guide. The kerf guide is adjustably mounted by improved means thereby permitting the kerf guide to maintain the desired spacing relationships with blades having different diameters.

We claim:

1. In a portable, power operated circular saw of the type having a motor driven, blade mounting shaft and a fixed blade guard adapted to enclose the teeth on the upper portion of a circular blade mounted on said shaft, the improvement comprising:

a. a kerf guide and means mounting the same adjacent said fixed blade guard and positioned so as to enter the kerf formed by a circular blade mounted on said shaft;

. a movable blade guard and other means mounting the same for swinging movement between open and closed positions about an axis parallel with said shaft and offset from the axis of rotation of the latter in a direction toward said kerf guide; and

c. said movable blade guard being shaped such that in the closed position thereof it encloses both said kerf guide and a substantial number of the teeth on the lower portion of a circular blade mounted on said shaft.

2. The improvement according to claim 1 wherein said movable blade guard has a forward end which is engaged by the work being cut, said movable blade guard, when in the closed position thereof, cooperating with the fixed blade guard to enclose the entire periphery of a circular blade mounted on said shaft except for an approximate l0 sector defined by said forward end and the adjacent portion of the fixed blade guard.

3. The improvement according to claim 2 further defined by, a formation in which said shaft is rotatably mounted, said formation having an annular bearing surface defining said first mentioned axis, said movable blade guard having a ring formation rotatably engaging said annular bearing surface.

4. The improvement according to claim 1 further defined by:

a. said saw having a motor housing adjacent one side of said fixed blade guard;

b. a manually operable blade guard retracting member pivotally mounted adjacent said one side of said fixed blade guard; and

c. connecting means extending between said member and said movable blade guard thereby to swing the latter about said axis upon pivoting movement of the former.

5. The improvement according to claim 1 further defined by, adjustment means supporting said kerf guide from said fixed blade guard, which adjustment means serves to permit mounting of the kerf guide in a plurality of positions in its own plane.

6. The improvement according to claim 5 wherein said adjustment means comprises:

a. a first element including cam means;

b. a second element including cam follower means engaged with said cam means; and

e. one of said elements being mounted from said fixed blade guard adjacent the rearwardmost portion thereof, the other of said elements being connected to said kerf guide and mounting the same for movement in its own plane and also for rocking the same in said plane during such movement thereby permitting a predetermined spacing to be maintained between the distal end of the kerf guide and circular blades of different diameters.

7. The improvement according to claim 6 wherein one of said cam means and cam follower means consists of a pair of slots and the other of said cam means and cam follower means consists of a pair of fasteners slidably received in respective slots, the interengagement between said slots and said fasteners serving to impart said movements to said kerf guide.

8. The improvement according to claim 7 wherein said slots are contained in a plane parallel to the plane of the blade and extend generally perpendicular to a radius of a circular blade of said shaft, which slots diverge in a generally upward direction.

9. In a portable, power operated circular saw of the type having a motor driven, blade mounting shaft and a fixed blade guard adapted to enclose the teeth on the upper portion of a circular blade mounted on said shaft, and a movable blade guard adapted, in the closed position thereof, to enclose the teeth on the lower portion of such blade, the improvement comprising:

a. a first element including cam means;

b. a second element including cam follower means engaged with said cam means;

c. a kerf guide having a distal end and a leading edge surface adjacent thereto; and

d. one of said elements being mounted adjacent the rearwardmost portion of said fixed blade guard, the other of said elements being connected to said kerf guide at the end thereof remote from said distal end and mounting the kerf guide so as to enter the kerf formed by a circular blade mounted on said shaft and with a predetermined spacing between said leading edge surface and the periphery of the blade and also with a predetermined distance of said distal end above the lowermost portion of said blade, said cam means and said cam follower means cooperating to permit movement of the kerf guide in its own plane, the interengagement between said cam means and said cam follower means causing said kerf guide to be rocked in its own plane, in response to such movement of the kerf guide, along a prescribed path thereby to maintain said predetermined spacing and said predetermined distance between the kerf guide and circular blades of different diameters.

10. The improvement according to claim 9 wherein one of said cam means and cam follower means consists of a pair of slots, the other of said cam means and cam follower means consists of a pair of fasteners slidably received in respective slots, said slots being in non-parallel relationship with each other.

1 1. In a portable, power operated circular saw of the type having a motor driven, blade mounting shaft and a fixed blade guard adapted to enclose the teeth on the upper portion of a circular blade mounted on said shaft, and a movable blade guard adapted, in the closed position thereof, to enclose the teeth on the lower portion of iuch blade, the {m rovement comprising:

a. a rst element [[10 u mg cam means;

b. a second element including cam follower means engaged with said cam means;

c. a kerf guide;

d. one of said elements being mounted from said fixed blade guard adjacent the rearwardmost portion thereof, the other of said elements being connected to said kerf guide and mounting the same so as to enter the kerf formed by a circular blade mounted on said shaft, said cam means and said cam follower means cooperating to permit movement of the kerf guide in its own plane and to rock the same in said plane during such movement thereby permitting a predetermined spacing to be maintained between the distal end of the kerf guide and circular blades of different diameters; and

. said blade guard, in the closed position thereof, enclosing said kerf guide and a substantial number of the teeth on the lower portion of a blade on said shaft.

12. The improvement according to claim 11 wherein said movable blade guard includes a forward end adapted to be engaged by the work being cut, said fixed blade guard and said movable blade guard, in the closed position of the latter, serving to enclose the entire periphery of a circular blade on said shaft except for an approximate 10 sector defined by said forward end and the adjacent portion of the fixed blade guard. 

1. In a portable, power operated circular saw of the type having a motor driven, blade mounting shaft and a fixed blade guard adapted to enclose the teeth on the upper portion of a circular blade mounted on said shaft, the improvement comprising: a. a kerf guide and means mounting the same adjacent said fixed blade guard and positioned so as to enter the kerf formed by a circular blade mounted on said shaft; b. a movable blade guard and other means mounting the same foR swinging movement between open and closed positions about an axis parallel with said shaft and offset from the axis of rotation of the latter in a direction toward said kerf guide; and c. said movable blade guard being shaped such that in the closed position thereof it encloses both said kerf guide and a substantial number of the teeth on the lower portion of a circular blade mounted on said shaft.
 2. The improvement according to claim 1 wherein said movable blade guard has a forward end which is engaged by the work being cut, said movable blade guard, when in the closed position thereof, cooperating with the fixed blade guard to enclose the entire periphery of a circular blade mounted on said shaft except for an approximate 10* sector defined by said forward end and the adjacent portion of the fixed blade guard.
 3. The improvement according to claim 2 further defined by, a formation in which said shaft is rotatably mounted, said formation having an annular bearing surface defining said first mentioned axis, said movable blade guard having a ring formation rotatably engaging said annular bearing surface.
 4. The improvement according to claim 1 further defined by: a. said saw having a motor housing adjacent one side of said fixed blade guard; b. a manually operable blade guard retracting member pivotally mounted adjacent said one side of said fixed blade guard; and c. connecting means extending between said member and said movable blade guard thereby to swing the latter about said axis upon pivoting movement of the former.
 5. The improvement according to claim 1 further defined by, adjustment means supporting said kerf guide from said fixed blade guard, which adjustment means serves to permit mounting of the kerf guide in a plurality of positions in its own plane.
 6. The improvement according to claim 5 wherein said adjustment means comprises: a. a first element including cam means; b. a second element including cam follower means engaged with said cam means; and c. one of said elements being mounted from said fixed blade guard adjacent the rearwardmost portion thereof, the other of said elements being connected to said kerf guide and mounting the same for movement in its own plane and also for rocking the same in said plane during such movement thereby permitting a predetermined spacing to be maintained between the distal end of the kerf guide and circular blades of different diameters.
 7. The improvement according to claim 6 wherein one of said cam means and cam follower means consists of a pair of slots and the other of said cam means and cam follower means consists of a pair of fasteners slidably received in respective slots, the interengagement between said slots and said fasteners serving to impart said movements to said kerf guide.
 8. The improvement according to claim 7 wherein said slots are contained in a plane parallel to the plane of the blade and extend generally perpendicular to a radius of a circular blade of said shaft, which slots diverge in a generally upward direction.
 9. In a portable, power operated circular saw of the type having a motor driven, blade mounting shaft and a fixed blade guard adapted to enclose the teeth on the upper portion of a circular blade mounted on said shaft, and a movable blade guard adapted, in the closed position thereof, to enclose the teeth on the lower portion of such blade, the improvement comprising: a. a first element including cam means; b. a second element including cam follower means engaged with said cam means; c. a kerf guide having a distal end and a leading edge surface adjacent thereto; and d. one of said elements being mounted adjacent the rearwardmost portion of said fixed blade guard, the other of said elements being connected to said kerf guide at the end thereof remote from said distal end and mounting the kerf guide so as to enter the kerf formed by a circular blade mounted on said shaft and with a predeteRmined spacing between said leading edge surface and the periphery of the blade and also with a predetermined distance of said distal end above the lowermost portion of said blade, said cam means and said cam follower means cooperating to permit movement of the kerf guide in its own plane, the interengagement between said cam means and said cam follower means causing said kerf guide to be rocked in its own plane, in response to such movement of the kerf guide, along a prescribed path thereby to maintain said predetermined spacing and said predetermined distance between the kerf guide and circular blades of different diameters.
 10. The improvement according to claim 9 wherein one of said cam means and cam follower means consists of a pair of slots, the other of said cam means and cam follower means consists of a pair of fasteners slidably received in respective slots, said slots being in non-parallel relationship with each other.
 11. In a portable, power operated circular saw of the type having a motor driven, blade mounting shaft and a fixed blade guard adapted to enclose the teeth on the upper portion of a circular blade mounted on said shaft, and a movable blade guard adapted, in the closed position thereof, to enclose the teeth on the lower portion of such blade, the improvement comprising: a. a first element including cam means; b. a second element including cam follower means engaged with said cam means; c. a kerf guide; d. one of said elements being mounted from said fixed blade guard adjacent the rearwardmost portion thereof, the other of said elements being connected to said kerf guide and mounting the same so as to enter the kerf formed by a circular blade mounted on said shaft, said cam means and said cam follower means cooperating to permit movement of the kerf guide in its own plane and to rock the same in said plane during such movement thereby permitting a predetermined spacing to be maintained between the distal end of the kerf guide and circular blades of different diameters; and e. said blade guard, in the closed position thereof, enclosing said kerf guide and a substantial number of the teeth on the lower portion of a blade on said shaft.
 12. The improvement according to claim 11 wherein said movable blade guard includes a forward end adapted to be engaged by the work being cut, said fixed blade guard and said movable blade guard, in the closed position of the latter, serving to enclose the entire periphery of a circular blade on said shaft except for an approximate 10* sector defined by said forward end and the adjacent portion of the fixed blade guard. 